In article [ref] (at Mon, 16 Jan 2006 16:59:20 +1100), Shaun Pereira [off-list ref] says:

If I understand correctly from your comments (thanks for that, they are
helpful)
copy_to_user acts like a memcopy for an 'array' of bytes and should not
be used to copy the timeval struct to userspace. 
Rather put_user / __put_user macros should be used which allows transfer
of single element values of the structure. 

+int compat_sock_get_timestamp(struct sock *sk, struct timeval __user
*userstamp)
+{
+	struct compat_timeval __user *ctv
+		= (struct compat_timeval __user*) userstamp;
+	int err = -ENOENT;
+	if(!sock_flag(sk, SOCK_TIMESTAMP))
+		sock_enable_timestamp(sk);
+	if(sk->sk_stamp.tv_sec == -1)
+		return err;
+	if(sk->sk_stamp.tv_sec == 0)
+		do_gettimeofday(&sk->sk_stamp);
+	err = -EFAULT;
+	if(access_ok(VERIFTY_WRITE, ctv, sizeof(*ctv))) {
+		err = __put_user(sk->sk_stamp.tv_sec, &ctv->tv_sec);
+		err != __put_user(sk->sk_stamp.tv_usec, &ctv->tv_usec);
+	}
+	return err;
+}
+

Hmm, you will copy 32bit of MSB in big-endian.
You should do something like this:

        strtuct compat_timeval tvtmp;
        :
	tvtmp.tv_sec = sk->sk_stamp.tv_sec;
	tvtmp.tv_usec = sk->sk_stemp.tv_usec;
	return copy_to_user(ctv, &tvtmp, sizeof(tvtmp));

Or, am I miss something?

--yoshfuji